The European Starling (Sturnus vulgaris) is known for its iridescent black plumage that catches the light with purple and green sheens. While these birds appear largely uniform in their glossy, speckled coloring, there are subtle yet consistent distinctions between the sexes. Observing these differences requires attention to specific physical traits and behavioral patterns, particularly during the breeding season. The comparative approach to identification reveals a complex division of labor in courtship and rearing the young.
Visual Identification of Male and Female Starlings
The most reliable visual difference is found at the base of the bill, a trait that becomes pronounced during the spring breeding season. When the bill turns bright yellow, the male displays a small, distinctive bluish or blue-grey spot at the base of the lower mandible. Conversely, the female exhibits a pinkish or reddish coloration at the same spot on her lower bill.
Another consistent physical marker involves the coloration of the eye. The male possesses a uniformly dark brown iris, giving the entire eye a dark appearance. The female often has a lighter, pale, or yellowish ring surrounding the outer edge of her iris, creating a faint, two-toned effect.
Differences in feather structure and coloration also exist, though they are more subtle. Male plumage tends to be more saturated and glossier, reflecting a more pronounced purple and green iridescence. Males also have longer, narrower throat feathers, which they can puff up during displays. The female’s feathers are generally duller, and she retains more of the white or buff feather tips, resulting in a more heavily spotted appearance outside of the breeding period.
Distinct Behavioral Roles Outside the Nest
Before nesting duties begin, the male takes on the primary role of advertising territory and attracting a mate through complex vocal displays. The male’s song is long and varied, incorporating a mix of whistles, clicks, rattles, and mimicry of other sounds. The complexity of this song, including the length of his song bouts and the size of his repertoire, signals his quality and age, which females use for mate selection.
During his song, the male engages in a physical performance, often fluffing his iridescent throat and breast feathers while fluttering his wings in a hunched posture. He is also responsible for selecting and defending the nesting site, which is always a cavity. Territorial defense against rival males is aggressive, involving a threat display known as the “Stare,” which can escalate into physical confrontation or “bill fencing.”
The female’s primary behavioral role at this stage is assessment and resource defense. She inspects the quality of the male’s song and the suitability of the nesting cavity he has chosen. Once paired, the female displays aggression toward other females during the pre-laying period to prevent her mate from attracting secondary partners. This behavior secures the male’s full commitment to parental duties.
Shared and Separate Parental Responsibilities
Once a pair bond is established, both starlings contribute to the construction of the nest within a chosen cavity. The male begins the process by filling the hole with bulky materials like dry grass, twigs, and weed stems. The female then takes over to finish the structure, adding a finer lining of soft materials, such as feathers, leaves, and fine bark.
After the female lays her clutch of four to six pale bluish eggs, incubation duties are shared between the pair for about 12 days. The female assumes the greater share of this task, doing most of the daytime incubation and always sitting on the eggs throughout the night. Both parents develop a brood patch, a featherless area of skin that transfers body heat directly to the eggs.
Upon hatching, the feeding of the altricial young becomes an intense, shared responsibility. Both the male and the female participate equally in foraging for and delivering food to the nestlings until they fledge (21 to 23 days). Both adults work together to maintain nest sanitation by diligently removing the young birds’ fecal sacs.